Art of signaling by electromagnetic waves.



I R. A. FESSENDEN.

ART OF SIGNALING BY ELECTROMAGNETIC WAVES.

APPLICATION FILED MAY 18, 1909.

1,080,271 Patented Dec. 2, 1913.

FIELIL I/I/I/IA lll lllnlnnnnn VIII wn'fiz s: T Z Y 71 I. INVETOR/ jib-all whomit may concern UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, or B ANT nocx, MASSACHUSET S, ASsIGNoE, EY MESNE ASSIGNMENTS, To SAMUEL M. KINTNER, E PITTSBURGH, PENNSYLVANIA, AND

-HALSEY M. BARRETT, OF BLOOMFIELD, NEWJERSEY, RECEIVERS.

I ART OF SIGNALING BY ELECTROMAGNETIC WAVES.

zgriginal application flledlayA, 1906, Serial No. 315,266. Divided and this application filed May 1 8, 1999.

Specification of Letters-Patent.

swarm. 496,726.

Be it known that 1,1REGLNALD s vnEN, a citizen of the United States, re-

-. s idi ng.at Brant Rock, in the State ofMassa- .chusetts, have invented certain'new and use- Improvements in the Art of Signaling by Electromagnetic Waves of which the following is ,a pecification.

My -iuvention relates generally to .wire-' less telegraphy .and more particularly to methods of tuning the circuit of the appa-- ratus for selective reception of signals, as herein more fully described.

- Inthe accompanying drawing forming a part' of this specification, ,Figures I, :II and III illustrate diagrammatically ldifierent combinations of elements of my improved apparatus and igs. and *Yshow in an and section a variable transformer. In the practice of my invention, I provide a capacity and inductance shunt to each other and in operative relation to the eiial, a d arecei e in Q e ativ 'r at e to the condenser and in uctance .circuitj, The aerial 1 isgrounded as at 2, and has a:

variable inductance 3 in series therewith. The aerial in Fig. I is also connected to inductances 4 and 6, in shunt to a condenser 5. iaThe inductance 4: is preferably variable and the inductance 6 forms the primary of a transformer having a secondary 7. Both 6 and 7 are referably constructed so as to be capable o adjustment, as illustrated in Fig. IV. 1 A receiver 8, telephone 9, potentiome'ter 10, inductance 11' and condenser 12 are arranged in the circuit of the secondary 7. The condensers 5 and 12 are preferably adjustable, as is also the inductance 11. The aerial is preferably tuned tothe frequency of oscillations which it is desired to receive, and also the shunt circuit 4, 5 and 6, either alone or in conjunction with the secondary circuit 7, 12, 8 and 11. The circuit 7, 12, 8 and 11 is also preferably tuned to the frequency which it is desired to receive.

In the construction shown in Fig. II, the aerial 1, which is grounded as at' 2,. is

connected in series with the inductance 14.

able condenser 13. The receiver 19 is con,

nected across the inductance 16. The circuit of the receiver 19 includes a variable inductance 18, an adjustable capacity 17,--

telephone 20, and potentiometer 21. .Con-

,tact points a and bare adjustable. Y

The construction shown in Fig. 111 is especially applicable for use for the prevention of interference. The aerial 1 grounded as at 2 and is connectedtothe variable inductances 3, 24 .and 25. aerial is also connected to inductances 2 7 and 28, whichare arranged in shunt. to the capacities or condensers 23 and 26. ,The inductances 27 .and 28' form. primaries whose secondaries are shown at 29 and 30.

.In' ,the circuit with these secondaries are. in-

, cluded the variable inductance 31 adjustable capacity 36, receiver34, potentiometer 35 and telephone or other indicating instrument 33. The ,trahsformers have preferably a variable ratio of L turns, :the construction shown in Fig. IV being conveniently used.

The receiving system, withthe exception of the circuit 1, 3,25, 26,28 and ,2, isppefgr.

ablyjunedto tHeTI-equenhywhich i sired to receive, while this circuit is jpreferably adjusted empirically so esteem out interference without weakening thereceived signals. Where, however, the sending station emits waves of two frequencies, the one cir-' cuit 1, 3, 24, 23, 27, and 2 is preferably adjusted to one frequency, and the circuit 1, 3, 25, 26, 28 and 2 to the other-frequency.

The variable transformer shown in Figs. IV and V consists of, two pairs of drums 37, 38, and 39, 40, of which the drums .37 and 40 are preferably formed of metalor other conducting material, and are mounted in suitable bearings so as to be capable of rotation,

while the drums 38 and 39 are'formed of insulating material, the drum 39 being rotatable within the drum 38 and adjustable in and out of the same by means of the threaded rod 41 passing through drum or cylinder 39. The-drums 37 and 38 are made of the same diameter and are adapted to be driven simultaneously by suitable connection, as, for

example, the sprocket chain 42,shown.., The drums 39 and 40 are also of the same diameter' and are connected by a sprocket chain 43 or other'suitable means. The drum or cylinder 40 is also adjustable longitudinally by means of .a screw 44. -A portion of a i v length of wire is wound on the drum 37, and

drum 39 and partially on the drum 40, and

by rotating these drums the wire can be wound off of one and on to the other. It will be observed that as the wire is wound off or on the drum 39, it is moved axially out of and into the drum 38, and that the coils on the drums 38 and 39 will form the members of a transformer which can be varied by rotating these drums in the manner stated.

.I am aware that the use of a shunt resonant circuit for producing selectivity in electromagnetic apparatus is old. I am also aware that the use of a secondary operatively connected to an inductance in parallel with a-condenser is old, where the short circuited coil of a short circuited dynamometer operates as a secondary. And I am also aware that this arrangement has been used inconnection with an untuned aerial.

The interference preventer may be used with four branch circuits with a sending station emitting two frequencies, in this case two of the branches are preferably tuned to the frequencies which it is desired to receive, and the other branches are used as balancing branches to cut out interfering signals.

This application is a division of my copending application No. 315,266, filed May oa er/1i 4th, 1903, (later issued as Patent No. 928,371,

of July 20th, 1909).

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is the following:

1. In a wireless telegraphy, the method of tuning two circuits coupled by a transformer, which comprises varying the amount of wire in the coils of the transformer by infinitesimal increments and meanwhile adjusting the tuning in the two circuits to adapt the entire tuning to present conditions with respect to amount of energy trans-' ferred and closeness of tuning.

2. In wireless telegraphy, the method of tuning two inductively coupled circuits by gradually altering the amount of wire in the coils of'the transformer and simultaneously varying the coupling of the transformer.

3. In wireless telegraphy, the method of tuning two inductively coupled circuits by varying both the coupling and the amount of wire in each coil of the transformer by infinitesimal increments, substantially. as described.

In testimony whereof I have hereunto signed my name this 11th day of May, 1909, in the presence of the two subscribed witnesses.

REGINALD A. FESSENDEN. Witnesses:

Jnssm E. BENT, FLORENCE M. LYON. 

